Rotatable electrical connectors which permit movement of one side of the connector with respect to the other side of the connector are known in the art. Typically, such connectors allow for 360 degree rotation of the two sides by the use of concentric annular coaxial contact surfaces and are designed to prevent twisting of cords connected thereto. For example, U.S. Pat. No. 4,583,798 discloses the use of a series of contact rings in alignment with contact elements, all disposed within a shell having an openended cylindrical bore. The contact rings are disposed on a barrel within the bore. The barrel is free to rotate about the bore as the cords attached to either end of the connector exhibit rotational movement, thereby preventing the cords from being twisted and kinked. Electrical contact is continuously maintained between the contact rings and the contact elements throughout the rotational movement.
U.S. Pat. No. 4,753,600 discloses a similar concept employing inner and outer copper circular rings. A pair of opposing plates are rotatably joined together by an axle around which the plates rotate so that during rotation, electrical current passes through both plates without interruption. Thus, for example, a tool being directed in a circular motion can be attached to the connector and can then be used continuously without concern of twisting or effective shortening of the electrical supply cord.
U.S. Pat. No. 4,026,618 discloses an electrical plug which is designed to be mounted to a wall socket. The electrical cord connected to the plug may be rotated to any point around a 360 degree path. Such a plug allows for a low profile (i.e., the plug extends outward a very short distance away from the wall socket) thereby allowing objects such as furniture to be positioned very close to the wall. If an electrical appliance is connected to the plug through the electrical cord, such a design allows the electrical cord to be turned around the plug as the orientation of the electrical appliance to the plug changes. These results are achieved by the use of a rotatable disk plate with concentric annular conductive ridges.
All of these patents have in common the fact that they are designed to allow free movement along a 360 degree path and are not designed to be set or held at any particular angular position.
The problem often arises that the orientation of the plug end of an electrical appliance prevents the use of an adjacent plug within the same electrical box. For example, the most common form of electrical outlet comes in pairs. A rotational feature allows for an electrical appliance such as a night light to make advantageous use of multiple plug electrical outlets, regardless of their original orientation against a wall or along an extension cord. However, in the prior art described above, the lack of a tight frictional contact between the two parts which rotate with respect to one another will not allow the electrical connector to remain in a desired fixed position. Also, any twisting of cords attached to the connector would provide sufficient force to change the connector's orientation. If an electrical appliance were directly attached to the connector, the resting position of the appliance in the outlet would depend upon gravitational forces instead of a desired functionally useful position (e.g., one that does not block other outlets or cause electrical cord to hang over other outlets) or an aesthetically pleasing position.
Certain types of plug-in appliances, such as clocks and lighting fixtures, have a required or preferred orientation but typically are furnished with an electrical plug whose orientation is fixed with respect to the appliance. Electrical wiring codes vary in different parts of the country. Some codes require outlets in the same electrical box to be positioned horizontally with respect to one another while other codes require outlets in the same electrical box to be positioned vertically with respect to one another. Such appliances are readily accommodated by an outlet of a given orientation but are not suitable for use with outlets oriented at 90 degrees from the given orientation.
There is still a need for a rotatable electrical connector which allows for movement between a limited angular range to accommodate different orientations of electrical plugs and outlets, which will stay fixed in a desired position unless physically moved and which can achieve these goals through a design that is simple to fabricate. The present invention fills that need.